Do the following:

grep -rnw '/path/to/somewhere/' -e "pattern"

• -r or -R is recursive,
• -n is line number, and
• -w stands match the whole word.
• -l (lower-case L) can be added to just give the file name of matching files.
• Along with these, --exclude or --include parameter could be used for efficient searching. Something like below:

grep --include=\*.{c,h} -rnw '/path/to/somewhere/' -e "pattern"

This will only search through the files which have .c or .h extensions. Similarly a sample use of --exclude:

grep --exclude=*.o -rnw '/path/to/somewhere/' -e "pattern"

Above will exclude searching all the files ending with .o extension. Just like exclude file it's possible to exclude/include directories through --exclude-dir and --include-dir parameter; for example, the following shows how to integrate --exclude-dir:

grep --exclude-dir={dir1,dir2,*.dst} -rnw '/path/to/somewhere/' -e "pattern"